In various fields of technology there is a need for increasingly smaller electronic devices. Such miniaturization requires greater integration of the circuits and their active components, and a reduction in the size of these components and their connection elements. Depending on the area of application of the electronic devices, there are also limitations with respect to the permissible techniques for manufacturing and assembling the circuit components and connection elements. This can make it difficult to use known microelectronics manufacturing processes, and may require that these processes be adapted.
Implantable electronic devices (such as implantable defibrillators or cardiac pacemakers, which have a liquid-tight biocompatible housing and an electronic component assembly arranged therein) have thus far primarily been manufactured using weldable wiring bands to connect the individual components of the component assembly. These wiring bands consist of metal conductors which are laminated on both sides with an insulation film. Design limitations result not only from the creepage distances and air clearances that must be maintained for electrical insulation, but also because reliable lamination of the films requires relatively high minimum conductor spacings, for example up to 0.6 mm.
Another disadvantage of the known wiring bands is that it is impossible to make conductor tracks cross in a wiring band. In addition, when the wiring bands bend, the laminated films create restoring forces that hinder free deformation of the bands. These restoring forces not only reduce the accuracy of fit of the deformed bands, but also lead to mechanical stresses in certain installation situations. The laminated metal conductors make the bands not very flexible, and not very suitable for evening out tolerances. All this has a detrimental effect on the long-term conductivity of electrical contacts, and can even lead to contacts tearing off of a component assembly (e.g., when subjected to vibration). This must be avoided in medical implants such as defibrillators or cardiac pacemakers.
The bands are manufactured in batches, with the bands being manually inserted one after another into various forming tools. These time- and cost-intensive processes make it difficult to meet common requirements for implantable devices, such as accuracy of fit and cleanliness. This leads to relatively high rejection rates, and therefore is economically disadvantageous.
In microelectronics, wire bonding processes are frequently used to make electrical contact between electronic components and supporting substrates (their conductor tracks or contact pads). Contact conductors are typically in the form of thin aluminum wires that are soldered or welded to the substrate and component. Holding the bond wires down and welding them onto the substrate produces strong forces, so bonding requires the use of special holders and fixation of the substrates. However, it is difficult to fix flexible substrates, especially in non-planar mounting positions. For example, they can be fixed by gluing electronic components in a housing by means of the flexible support before contact is made. In the manufacturing of implantable electronic devices the use of adhesives is detrimental, since glue fumes represent a health risk and have a negative effect on the electronic behavior of the implant.